On a sunny afternoon in early August, the hot air rippled above a sandbar in Casco Bay as a group of researchers dove into the water. Wearing wetsuits and flippers, they swam out over sand, rocks and kelp until they reached their destination: a verdant seagrass meadow. 

Long, thin ribbons of bright green stretched out in the water, flattened by the strong current. Small fish swam in and out of the grass, as crabs and lobsters crawled underneath. At one point, a seal drifted by.

The divers were there to collect a type of eelgrass called Zostera marina. It’s the predominant species of seagrass in Maine. Unlike kelp and other seaweeds, which are algae, seagrasses are flowering plants that grow underwater. 

Seagrass shelters the young of many marine species, improves water quality and stores some of the excess carbon released by the burning of fossil fuels. Beds of seagrass also absorb wave energy, reducing erosion and buffering coastal communities from storms.

These underwater meadows used to grow abundantly along the Maine coast. But they’ve declined significantly in recent decades. The data measuring this decline is imperfect, and efforts to track it are ongoing. But according to the Maine Department of Environmental Protection’s best estimates, the state had more than 30,000 acres of seagrass beds in the 1990s. Since then, some regions of Maine have lost more than half of their seagrass beds.

Scientists say they haven’t collected enough data to pinpoint the exact cause of the decline, and they don’t expect to find one simple culprit. Rising temperatures, coastal development, nutrient pollution, harmful algal blooms, invasive species and worsening storms may all be playing a role. Seagrass meadows have declined not just in Maine but around the world, and are considered one of the ecosystems most vulnerable to climate change and other human activity.

These meadows are important for the ocean’s biodiversity because they are “the world’s greatest kindergarten” for young sea creatures, said Glenn Page, leader of the dive team and executive director of the Collaborative for Bioregional Action Learning and Transformation (COBALT), a Portland-based group working to restore coastal ecosystems. 

Page’s diving team is at the heart of a project involving Bowdoin College, the Casco Bay Estuary Partnership and other collaborators called Team Zostera, which aims to study eelgrass reproduction and test methods to harvest, store and transplant the plant’s seeds. Their effort is part of a larger seagrass conservation network in Casco Bay that has sprung up in recent years,  hoping to better understand the plant and restore it to places where it has been lost. 

‘We don’t have the full picture’

Mainers’ efforts to better understand and protect these marine meadows stretch beyond Casco Bay, and date back to at least the 1990s.

“A lot of our small, rural, coastal economies depend on the marine ecosystem,” said Cheyenne Adams, a biologist at the Maine Department of Environmental Protection.

The Department of Marine Resources mapped Maine’s seagrass meadows from 1993 to 1997 and again from 2001 to 2010, but didn’t have funding to continue. The Department of Environmental Protection mapped Southern Maine and Casco Bay from 2013 to 2022, but that  left a long data gap in other places, until state legislators funded a new statewide program, which started in 2023 and is run by Adams. 

She and her colleagues divided the coastline into five regions and have been mapping one region per year. 

The results so far show significant declines. Between 2018 and 2022, Casco Bay lost more than half of its seagrass acreage. Midcoast Maine has lost about 60 percent since 2005. Penobscot Bay has lost about 35 percent since the mid-2000s. The Acadia region has lost more than half since the late 2000s. And many of the remaining meadows are less dense than they used to be. Downeast Maine is still being mapped.

Why this is happening is the “million dollar question,” Adams said. “It’s probably not a simple answer.”

Climate change and rising temperatures are likely contributing factors, as are the more severe storms the state has seen in recent years, which can uproot seagrass or bury it with sediment. Invasive green crabs moving north with warmer waters can also tear and uproot the grass.

Worsening water quality is another suspect, with nutrient runoff from land fueling harmful algal blooms that shade the seagrass, starving it of the sunlight it needs to photosynthesize.

Identifying these stressors is a key first step to protecting and eventually restoring seagrass meadows. 

“There is concern about being able to restore these systems in time, before it’s lost. But I also think that we don’t have the full picture right now,” Adams said. “We don’t want to restore an area if it’s just going to die.”

At the same time, she said, it’s worth laying the groundwork now.

Janelle Goeke, a staff scientist at the Casco Bay Estuary Partnership, agreed. Her organization is coordinating the grant that funds Team Zostera and several other related seagrass projects. 

“By starting this process of understanding earlier on, we’re hopefully putting ourselves in a better situation for restoration down the road,” she said.

Researchers have seen some evidence that restoration might be possible. In Casco Bay, some of the eelgrass lost between 2018 and 2022 has come back recently on its own, and her organization is working with the U.S. Fish and Wildlife Service on aerial drone surveys to measure this change in more detail. Goeke suspects this recovery is because water temperatures have been cooler in the past two years.

Eelgrass has a higher metabolism at higher temperatures, meaning the warmer the water, the more light an eelgrass plant needs for its higher rate of photosynthesis. Plants that are getting little light in warming temperatures are at risk of dying off.

Goeke has noticed that the eelgrass beds closest to shore seem to be suffering the most, while those growing around outer islands with more exposure to the open ocean are healthier. These meadows ebb and flow naturally, making it hard to know whether any one change will be permanent, she said. But their dynamic nature also offers researchers hope.

“If we can get the conditions right, there is a chance for it to come back,” she said.

Mother meadows 

As they kicked slowly over the eelgrass meadow, the researchers from Team Zostera looked for blades of grass bearing seeds, plucking them from the sand and collecting them in mesh bags.

Within an hour, the limit of their oxygen tanks, the four younger divers — Savanna Deer, the group’s dive safety officer in training; Ella Kennedy and Hazel Johnson, both students at Bowdoin College; and Dillon Jenkins, a high school student from Scarborough — had collected more than 3,000 shoots. Page had collected nearly 2,000.

“The reproductive shoots were everywhere,” he said. “You couldn’t turn without seeing them.”

This eelgrass bed, between Haskell and Upper Flag Islands, is healthy enough that it has been designated a “mother meadow,” with enough shoots and seeds to spare for other areas.

The researchers are hoping to collect seeds from healthy mother meadows and transplant them to places where eelgrass has been lost and needs help coming back. They are testing out ways to process and plant the seeds, preparing for larger scale restoration.

They are also on a mission to build awareness and to make connections with others who care about the ecosystem. 

While the divers were out in Casco Bay, about a dozen volunteers gathered on land, at Bowdoin College’s Schiller Coastal Studies Center in Harpswell. 

Coils of eelgrass shoots from the previous day’s dive sat piled on folding tables outside the marine laboratory. Space at the facility is at a premium, so the volunteers were tasked with collecting just the parts of the shoots with seeds, which look like longer, skinnier, transparent pea pods and are called spathes.

Inside the lab, pipes delivered seawater from Harpswell Sound into rows of tanks containing an assortment of marine life. A dozen were reserved for the eelgrass spathes. Jaret Reblin, associate director for science at the center, said he expected all of those tanks to be filled after two weeks of dives. As the spathes sat in the water, their seeds would settle out and be collected for research — and, potentially, to be transplanted elsewhere.

That day’s group included several chaplains and pastors who had come to Harpswell with the BTS Center, a nonprofit that grew out of the former Bangor Theological Seminary and now helps spiritual leaders address climate change. 

Alison Patton, senior pastor at the United Church of Christ’s First Congregational Church in South Portland, said that although she’s not a scientist she knows “we need to figure out how to live sustainably.” 

After eight hours of plucking, the volunteers were sweaty and sticky, with hands pruned from saltwater. They had managed to go through nine bags of eelgrass, roughly 18,000 spathes.

Researchers from the University of Maine’s Darling Marine Center had also come to spend the day sorting eelgrass spathes. They are preparing to launch their own restoration effort in the Damariscotta River’s Great Salt Bay.

Team Zostera has also worked with the Passamaquoddy, or Peskotomuhkati in their own language, to incorporate their cultural knowledge into the seagrass restoration effort.

“Everything is connected,” said Dwayne Tomah, director and curator of the Waponahki Museum at Sipayik, or Pleasant Point. Tomah has been helping Team Zostera translate seagrass-related terms into Passamaquoddy, naming and describing eelgrass meadows in the language. He’s also part of a theatrical performance about seagrass that the group has been touring around Maine. 

“The language is how we view the world,” he said. “People, in general, look at the environment as a resource. And we don’t look at it as a resource. We look at it as our relatives.” 

Hugh Akagi, the chief of the Peskotomuhkati Nation at Skutik, on the Canadian side of the border, is also involved in Team Zostera’s work and echoed this sentiment. 

Seagrass had helped nourish his community in Passamaquoddy Bay for thousands of years, he said, but now, because of ongoing development along the coast, the ecosystem’s health is “very bleak.” 

While there is no silver bullet solution, Akagi said, he believes government policies need to change to better protect the environment. In the meantime, he said gathering evidence of what’s happening and educating people can help.

Akagi has seen other species come back from the brink. This includes moose, which were once nearly wiped out in New Brunswick but rebounded thanks to conservation efforts. He thinks the region’s seagrass, and all it supports, has a chance as well — if people act quickly.

“There’s hope,” he said. “We need to take advantage of that now.” 

This story was originally published by The Maine Monitor, a nonprofit civic news organization. To get regular coverage from The Monitor, sign up for a free Monitor newsletter here.